Filter cigarettes typically comprise a rod of tobacco cut filler surrounded by a paper wrapper and a cylindrical filter aligned in end-to-end relationship with the wrapped tobacco rod and attached thereto by tipping paper.
Filters in conventional cigarettes may comprise one or more segments of filtration material for the removal of particulate and gaseous components of the mainstream smoke. In conventional filter cigarettes, the filter usually consists of a plug of cellulose acetate tow wrapped in porous plug wrap. From the Swiss patent CH394912 it is known to include one or more transparent sections in the tipping paper in order to render the interior of the filter cigarette at least partially visible. Unfortunately, in use, the transparent section becomes quickly opaque as particles from the mainstream smoke deposit on the inside of the transparent section. Thus, the possibility to observe the inside of the filter is quickly lost.
It would be desirable to provide a smoking article that allows viewing the inside of at least a part of the filter throughout the entire use of the smoking article.